Automatic choke air heater



F. W. HAMILTON AUTOMATIC CHOKE AIR HEATER Original Filed Feb. 15, 1952 March 10, 1959 n 4 4 I 4 m I mw MAZWQQKN1II V4 HH.| :l a 2 .r P w d flfiwflm 4 ii 5, 4 w M w 1 a 2 2 United States Patent AUTOMATIC 'CI-IOKE AIR HEATER Francis W. Hamilton, Detroit,Mich., assignor to Chrysler Corporation, Highland Park, Mich, a corporation of Delaware 1 Claim. (Cl. 257-241) This invention relates to an improved manifold for an internal combustion engine and more particularly to a manifold having a circuitous passage formed integrally therein for heating air for subsequent delivery to a temperature responsive choke control element.

This application comprises a division of my copending application Serial No. 271,807, filed February 15,1952, v

now abandoned.

Automatic choke controls which are operable in response to engine temperature are frequently provided on carburetors and generally provide a bimetallic element and means to expose this element to heat from the ex- I haust manifold. Expansion and contraction of the bi metallic element is utilized to move a choke valve controlling the admission of air to the carburetor and engine intake manifold. Devices of this type generally have apparatus for passing atmospheric air in heat exchange relation with the exhaust manifold and conducting this heated air to the bimetallic element. This apparatus frequently uses a box strapped to the outside of the manifold for heating the air.

It is a principal object of this invention to provide a manifold having a circuitous passage for atmospheric air integrally formed therein and to thereby eliminate the additional components required by the above mentioned apparatus. The air passage which is integral with the manifold also permits the tubing for conducting heated air to the bimetallic element to be connected to the manifold at a preselected location adapted to minimize the length of the tubing and thereby minimize the heat loss.

It is an additional object of the invention to provide a manifold having a cavity therein adapted to serve as a circuitous air passage and having this cavity formed in a manifold wall or surface that on assembly will abut the cylinder block so that the cylinder block will serve as a wall of the circuitous passage. This construction facilitates casting of the manifold and cleaning of the circuitous passage.

In the drawings:

Fig. 1 is a vertical section of a carburetor having an automatic choke control;

Fig. 2 is a partial elevation of a manifold incorporating my invention;

Fig. 3 is a vertical section taken on the line 3-3 of Fig. 2; and

Fig. 4 is a partial section taken on the line 4-4 of Fig. 2.

In Fig. 1 a carburetor 10 is secured to an engine intake manifold 11. The carburetor is of conventional construction and will be described in connection with the automatic choke control with which my improved manifold is intended to cooperate. The carburetor comprises a body 12, air horn 13, insulator 14, and a body flange 15. These parts are assembled vertically and are provided with a tubular fuel mixture passage 16. The passage 16 has a restricted portion at 17 which is adapted to produce a venturi effect in a manner well-known in the art. The air horn 13 serves as an inlet to the fuel 2,876,999 Patented Mar. 10, 1959 2 mixture passage 16. The egress of the fuel mixture from the passage 16 to the engine intake manifold is controlled by a throttle valve 19. The main fuel jets 20 are located in the restricted portion 17 in a conventional manner and an idling jet is illustrated at 22.

A conventional choke valve 24 is pinned to a shaft 26 which is rotatably mounted transversely of the air horn. The position of the choke valve 24 in the air horn 13 may be varied by rotation of the shaft 26 and this position will determine the restriction to the passage of air from the air horn 13 through the mixture passage 16. The valve 24 is preferably mounted oif center on the shaft 26 so that the weight of the valve and the passage of air will tend to maintain the valve in its open position.

A chamber 28, which is provided on the side of the air horn 13, houses a bimetallic coil element 30 which has one end secured tothe shaft 26 and its other end abutting a portion 32 of the air horn 13. A tube 34 is connected to the chamber 28 and extends to my novel exhaust manifold 36 which will furnish a supply of heated atmospheric air to the tube 34. A passage 38 connects the chamber 28 with the lower portion of the mixture passage 16. The suction present in theintake manifold of the engine draws air from chamber 28 through passage 38 and this air is replaced by warm air drawn from the tube 34 and a circuitous passage to be described herein and provided in my novel manifold. Thetemperature of the coil element 30 is thus dependent upon the engine operating temperature and the expansion and contraction of the coil element 30 rotates the shaft 26 to position the valve 24 in a position which is controlled by engine temperature.

In Figs. 2, 3 and 4 a manifold 36 which incorporates my invention and which is of a type commonly used on a V-8 engine is illustrated. This exhaust manifold 36 is provided with a horizontally extending main exhaust passageway 40 having a plurality of ports 42 communicating therewith and adapted to deliver exhaust gases from the engine cylinder. The portion of the engine which is visible is referred to herein as the engine body member and is designated by the numeral 44. It is to be understood that the body member 44 represents a conventional engine block or cylinder head depending upon the valve arrangement incorporated in the engine. An outlet 46 communicates with the main passageway 40 and is adapted to be connected in a conventional manner to an exhaust pipe, muffler and tail pipe assembly, not shown. The manifold 36 is provided with lugs 48 adapted to be bolted to the engine body member 44 by bolts 50.

The manifold 36 has a cavity 52 integrally formed therein and intersecting a sealing surface 54 of the manifold which is adapted to abut the engine body member 44. The manifold 36 is also provided with an opening 56 which is in communication with the cavity 52 and adapted to admit atmospheric air thereto. The engine body member 44 and the manifold 36 thus cooperate so that the cavity 52 operates as a compartment when the manifold is assembled on the engine body member. The cavity or compartment 52 is also provided with an out let 58 having a reduced cross sectional area and located at a remote portion of the cavity so that the cavity or compartment 52, opening 56 and outlet 58 cooperate to form a circuitous passage for atmospheric air in heat exchange relation with the exhaust manifold. The outlet 58 connects with a passage 60 in which the open end 64 of a tube 62 having a cross sectional area comparable to that of the outlet 58 is seated. The tube 62 extends through the manifold and has an end which projects on the exterior thereof. The tube 34, as previously mentioned, is connected to the tube 62 so that the air may be conducted to chamber 28 of the automatic choke mechanism. Although some heating of the air may occur in the tube 62 it is intended that the principal heating occur in the circuitous passage defined by the opening 56, cavity or compartment 5,2 and outlet 58.

It is to be understood that although the drawings and description have referred tosealing surface 54 as abutting the engine body member 44 a conventional gasket may be interposed between the manifold and engine body member in accordance with the usual practice and under such circumstances the gasket may be considered as a part of the engine body member for purposes of terininology herein.

I claim:

A heating system for producing hot air for use in an automatic choke on an internal combustion engine comprising an exhaust manifold adapted to be secured to an exhaust pipe and having walls defining a first passage? way for conducting exhaust gases from the engine to the exhaust pipe, said exhaust manifold including integral wall structure defining a cavity and an entrance to said cavity, said cavity being located outside of the physical confines of said first passageway and further being located wholly on one side of the above mentioned first passageway, said entrance being in communication with the atmosphere and having a cross sectional area which is materially smaller than the cross sectional area of said cavity, said wall structure further defining an outlet of materially reduced cross sectional area compared to the cross sectional area of said cavity with said outlet substantially diametrically opposed to the above mentioned entrance relative to said cavity, tubing having a aaae .4 a cross sectional area comparable in size to the cross sectional area of said outlet; said tubing having a first end secured in fluid flow communication with the outlet of said cavity and serving to close said outlet except for the communication from said cavity afi'orded through the interior of said tubing, said tubing penetrating said first passageway for a substantial distance and being in position to be directly contacted by the exhaust gases in said first passageway, said tubing further having a portion thereof remote from said first end penetrating a wall of said manifold to present a portion of said tubing externally of said manifold for connection to an automatic choke whereby said cavity and said tubing cooperate to define a second passageway having a reduced entrance and outlet and a localized portion adjacent the entrance thereto provided with a materially enlarged cross sectional area.

References Cited in the file of this patent UNITED STATES PATENTS 972,547 Law Oct. 11, 1910 2,571,181 Ball Oct. 16, 1951 2,653,588 Meinzinger et a1. Sept. 29, 1953 2,667,154 Ball Jan. 26, 1954 2,715,520 Boyce Oct. 18, 1955 FOREIGN PATENTS 1,082,026 France Dec. 24, 1954 

